Optical filters carefully transfer light in a specific range of wavelengths or colors while obstructing what remains. These dyed plastic or glass devices are placed in the optical path. They are described by their frequency response, and this identifies how the scale and stage of each frequency component of an incoming signal is altered by the filter.
What Is Astigmatism?
Astigmatism is an extremely common eye condition that affects both children and adults. It occurs when there is an imperfection in some part of your cornea, the clear tissue that covers your iris.